An instant water heater which heats water flowing between two immersed electrodes.
This invention relates to water heaters of the type which heat water that flows between two electrodes, rather than by providing a hot element which is contacted by the water. In this invention, the water is heated by electrical current flowing through the water when the water is between the two electrodes.
So called xe2x80x9cinstantxe2x80x9d water heaters differ from conventional water heaters by their lack of a storage tank for hot water. Instead of heating and storing water for future usage, instant water heaters accept cold or cool water, heat it, and deliver it directly to the user point on demand. Such heaters find their most common usages in sink faucets, showers and tubs, although they can be provided for any other usage that requires hot water.
Among their advantages is that they can be placed very near to the use point. Pipes of substantial length need not be emptied of cold water before hot water arrives from a central source, for example. Also, it is much easier to run an electrical circuit to a distant heater than to provide a distant tank, or a long pipe to convey hot water from a central source to a distant use point.
Legionnaire""s Disease is well-known as a consequence of water stored for long periods at moderate temperature. Having no storage of the water at all profoundly reduces risk of such disease.
Presently-known instant water heaters do have major disadvantages, including short product life, short service life, liability to water damage, moderate rates of flow, high energy consumption, and release of metal ions into the water.
Yet another disadvantage of existing instant water heaters is their inability to accommodate varying input voltages and amperage along with water flow that matches their intended use. A complaint often heard is that a wrong instant water heater was purchased from among many different models. The necessary wide range for variables, such as voltage and circuit breaker amperage, and service flow in gallons is simply too confusing for many customers.
It is yet another disadvantage of existing instant water heaters that they often burn out or break coils due to water hammering, air in the water lines, or current overloads. These pose an electrical danger from direct contact of live broken coil ends to the water. Then electrical current passes directly into the water. Manifolds are connected to ground with a grounding wire corrode, and it is only a matter of time before a corroded manifold or a burned out coil releases a full current load into the water and out a faucet or other plumbing fixture when in use, to the risk of the user.
It is an object of this invention to provide an instant water heater whose energy consumption is less than that of known conventional types, and whose lifetime is longer, with less frequent service requirements.
It is another object of this invention to provide a water heater whose output temperature can readily be adjusted, and which is electrically very safe.
It is another object of this invention to provide electrodes for an instant water heater which are resistant to wear and corrosion, and which tend more to resemble thermal insulators than to metal conductors as to thermal characteristics.
It is another object of this invention to provide an instant water heater that has grounding screens which are resistant to corrosion, rather than conventional metallic grounding screens or grounding manifolds.
It is another object of the invention to provide a water heater that will accommodate a surprisingly large range of available input voltages and water flows, with only two simple installation adjustments.
It is another object of the invention to prevent shock hazard by introducing a corrosion resistant field obstructor at both the inlet and the outlet of the water heater. These field obstructors eliminate dangerous electrical leakage current that egress the water heater electrodes.
It is yet another object of the invention to provide non-corrosive grounding screens made of a conductive polymer placed at the inlet and outlet of the water heater further eliminating the possibility of inevitable electrical shock due to corrosion or breakage in the system.
It is yet another object of the invention to eliminate corrosion and extend the life of a water heater by eliminating all contact of liquid to metal throughout the entire system, thus eliminating electrolytic, galvanic and all other forms of corrosion. The additionally provides the advantage that metallic ions are not infused into the hot water supply.
An instant water heater according to this invention comprises a heating chamber having an inlet and an outlet. Water to be heated enters the chamber through the inlet, and after being heated, exits through the outlet to a point of use.
A pair of spaced-apart electrodes is mounted in the chamber, so disposed and arranged that a suitable proportion of the water passes between them so as to be heated by current that flows through the water from one electrode to the other.
The temperature to which the water is heated is independent of the rate of flow. It can be regulated by adjusting an electrical current amplitude flow control device (herein frequently called a xe2x80x9ccurrent gatexe2x80x9d) that is disposed between the electrodes. This current gate adjusts the amount of confronting areas of the electrodes. Adjusting the spacing between the electrodes, or shifting them relative to each other can also or instead regulate the attained temperature of water.
According to this invention, the electrodes are principally formed of, and their exposed surfaces are specifically made of, an electrically conductive polymeric resin. According to a preferred but optional feature of the invention, the polymer is loaded with graphite or with graphite combined with carbon fibers to reduce the bulk electrical resistance of the material and provide suitable conductivity for the electrode.